ARVC protocol (MRI)

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The cardiac MRI ARVC protocol encompasses a set of different MRI sequences for the cardiac assessment in case of suspected arrhythmogenic right ventricular cardiomyopathy.

Note: This article aims to frame a general concept of a cardiac MRI protocol in the above setting.

Protocol specifics will vary depending on additional clinical questions, differential diagnosis, MRI scanner type, specific hardware and software, radiologist and perhaps referrer preference, patient factors e.g. arrhythmia or breathing problems or implants, specific indications and time constraints.

Indications

1.5 vs 3 tesla

Cardiac MRI examinations can be generally performed on both 1.5 and 3 tesla.

The acquisition at a 3 tesla system requires a lot of adjustments and careful shimming to avoid flow and dark banding artefacts, especially concerning steady-state free precession cine imaging.

Due to potential problems in regard to cine imaging at 3T, a cardiac MRI for the assessment of arrhythmogenic right ventricular cardiomyopathy might be preferably conducted on a 1.5 tesla system.

Applications that may benefit from increased field strength is late gadolinium enhancement .

Patient preparation

Checking indications, contraindications, explanation of the examination and obtaining informed consent is obvious as in other examinations.

Beyond that patient preparation for cardiac MRI includes the following:

  • instruction how to breathe
  • an electrocardiogram signal need to be acquired

Patient positioning

A cardiac MRI is conducted in the supine position.

Technical parameters

Coil

Multi-phased-array coils are recommended.

  • anterior surface coil, posterior coil
  • cardiac coil
Scan geometry
  • in-plane spatial resolution: will vary with the sequence
  • field of view (FOV):  will vary, for most planes a FOV ≤320 mm is recommended
  • slice thickness: for cine images especially right ventricular stack consider 5-6 mm
Planning

The cardiac imaging planes differ from the normal axial, coronal and sagittal body planes :

  • overview
    • angulation: strictly axial
    • volume: from the thoracic inlet to the diaphragm
  • horizontal long axis view or 4-chamber view (4ch) 
    • angulation: along the left ventricular long axis through the apex and the centers of the mitral and tricuspid valves
    • volume: including the anterior and inferior wall or a single slice
  • left ventricular vertical long axis view or 2-chamber view (2ch)
    • angulation: along the left ventricular long axis through the left ventricular apex and the center of the mitral valve
    • volume: including septum and left ventricular free wall or single slice
  • sagittal left ventricular outflow tract (LVOT) or 3-chamber view (3ch) 
    • angulation: through the left ventricular apex,  the center of the mitral valve and the left ventricular outflow tract and aortic valve
    • volume: including the anterolateral and inferoseptal left ventricular wall
  • short-axis view (sax)
    • angulation: perpendicular to the left ventricular long axis
    • volume: stack usually including the atrioventricular valves and the cardiac apex or 3 single slices through basal, midventricular and apical zones
  • right ventricular vertical long axis view or 2-chamber view (2ch) 
    • angulation: along the right ventricular long axis through the apex, the center of the tricuspid valve and through the right ventricular outflow tract
    • volume: single slice, or a stack including the septum and right ventricular free wall
  • right ventricular transaxial view
    • angulation: strictly axial to the body axis
    • volume: including the whole right and left ventricles and the pulmonary valve
  • sagittal right ventricular outflow tract (RVOT)
    • angulation: sagittal oblique along the axis of the main pulmonary artery
    • volume: consider a stack

Sequences

Standard sequences
  • T2 black-blood or SSFP
    • purpose: overview, depiction of the cardiac surroundings and great vessels
    • technique: T1 black-blood, T2 black-blood, SSFP ideally over 1-2 breath-holds
    • planes: axial (increased FOV)
  • cine imaging
    • purpose: left ventricular wall motion, left ventricular volumetry
    • technique: cine SSFP or spoiled GRE
    • planes: 2ch, 4ch, 3ch and short-axis views, RV VLA, transaxial stack, sRVOT 
Optional sequences
  • T1 weighted imaging
    • purpose: for the evaluation of fatty deposits
    • technique: T1 black-blood with and without
    • planes: transaxial stack
  • late gadolinium enhancement (C+)
    • purpose: for the evaluation of myocardial fibrosis
    • technique: 2D and 3D IR GRE, PSIR
    • planes: 2ch, 4ch, 3ch and short-axis views
    • TI as determined by TI scout (Look-Locker) or fixed TI (PSIR)

(*) indicates optional planes

Practical points

The following considerations can be made in certain conditions:

  • single-shot modules or free breathing with real-time image acquisition in patients with difficulties to hold their breath
  • abdominal bands in profound respiratory motion
  • peripheral pulse gating in patients with a weak ECG signal
  • postponing the exam in patients with severe pleural effusion and related ghosting artifacts and breathing problems until after pleural drainage
  • cine imaging
    • volumes need to be obtained for both ventricles
    • a stack of sagittal cine images through the right ventricular outflow tract can be considered
  • late gadolinium enhancement
    • inversion time (TI) should be nulled for the right ventricle